Different types of levers acting in different ways on cross bars are previously known. In some embodiments the cross bar or equivalent part is more or less floating while in other embodiments the cross bar is closely guided. Furthermore, the levers acts directly or by means of an intermediate part on the cross bar giving a more or less extended contact surface between the lever or intermediate part and the cross bar. The force application systems of the prior art normally form some kind of eccentric giving a nearly constant transmission of the force of the brake actuator in the form of a pneumatic cylinder or the like.